linux/tools/perf/util/unwind-libunwind.c
Jiri Olsa 382619c07f perf tools: Speed up report for perf compiled with linwunwind
When compiled with libunwind, perf does some preparatory work when
processing side-band events. This is not needed when report actually
don't unwind dwarf callchains, so it's disabled with
dwarf_callchain_users bool.

However we could move that check to higher level and shield more
unwanted code for normal report processing, giving us following speed up
on kernel build profile:

Before:

  $ perf record make -j40
  ...
  $ ll ../../perf.data
  -rw-------. 1 jolsa jolsa 461783932 Apr 26 09:11 perf.data
  $ perf stat -e cycles:u,instructions:u perf report -i perf.data > out

   Performance counter stats for 'perf report -i perf.data':

    78,669,920,155      cycles:u
    99,076,431,951      instructions:u            #    1.26  insn per cycle

      55.382823668 seconds time elapsed

      27.512341000 seconds user
      27.712871000 seconds sys

After:

  $ perf stat -e cycles:u,instructions:u perf report -i perf.data > out

   Performance counter stats for 'perf report -i perf.data':

    59,626,798,904      cycles:u
    88,583,575,849      instructions:u            #    1.49  insn per cycle

      21.296935559 seconds time elapsed

      20.010191000 seconds user
       1.202935000 seconds sys

The speed is higher with profile having many side-band events,
because these trigger libunwind preparatory code.

This does not apply for perf compiled with libdw for dwarf unwind,
only for build with libunwind.

Signed-off-by: Jiri Olsa <jolsa@kernel.org>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/r/20190426073804.17238-1-jolsa@kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
2019-05-15 16:36:46 -03:00

96 lines
2.3 KiB
C

// SPDX-License-Identifier: GPL-2.0
#include "unwind.h"
#include "map.h"
#include "thread.h"
#include "session.h"
#include "debug.h"
#include "env.h"
#include "callchain.h"
struct unwind_libunwind_ops __weak *local_unwind_libunwind_ops;
struct unwind_libunwind_ops __weak *x86_32_unwind_libunwind_ops;
struct unwind_libunwind_ops __weak *arm64_unwind_libunwind_ops;
static void unwind__register_ops(struct thread *thread,
struct unwind_libunwind_ops *ops)
{
thread->unwind_libunwind_ops = ops;
}
int unwind__prepare_access(struct thread *thread, struct map *map,
bool *initialized)
{
const char *arch;
enum dso_type dso_type;
struct unwind_libunwind_ops *ops = local_unwind_libunwind_ops;
int err;
if (!dwarf_callchain_users)
return 0;
if (thread->addr_space) {
pr_debug("unwind: thread map already set, dso=%s\n",
map->dso->name);
if (initialized)
*initialized = true;
return 0;
}
/* env->arch is NULL for live-mode (i.e. perf top) */
if (!thread->mg->machine->env || !thread->mg->machine->env->arch)
goto out_register;
dso_type = dso__type(map->dso, thread->mg->machine);
if (dso_type == DSO__TYPE_UNKNOWN)
return 0;
arch = perf_env__arch(thread->mg->machine->env);
if (!strcmp(arch, "x86")) {
if (dso_type != DSO__TYPE_64BIT)
ops = x86_32_unwind_libunwind_ops;
} else if (!strcmp(arch, "arm64") || !strcmp(arch, "arm")) {
if (dso_type == DSO__TYPE_64BIT)
ops = arm64_unwind_libunwind_ops;
}
if (!ops) {
pr_err("unwind: target platform=%s is not supported\n", arch);
return 0;
}
out_register:
unwind__register_ops(thread, ops);
err = thread->unwind_libunwind_ops->prepare_access(thread);
if (initialized)
*initialized = err ? false : true;
return err;
}
void unwind__flush_access(struct thread *thread)
{
if (!dwarf_callchain_users)
return;
if (thread->unwind_libunwind_ops)
thread->unwind_libunwind_ops->flush_access(thread);
}
void unwind__finish_access(struct thread *thread)
{
if (!dwarf_callchain_users)
return;
if (thread->unwind_libunwind_ops)
thread->unwind_libunwind_ops->finish_access(thread);
}
int unwind__get_entries(unwind_entry_cb_t cb, void *arg,
struct thread *thread,
struct perf_sample *data, int max_stack)
{
if (thread->unwind_libunwind_ops)
return thread->unwind_libunwind_ops->get_entries(cb, arg, thread, data, max_stack);
return 0;
}